Cathode glow indicator tube



March 22, 196e Filed OCb. 5, 1962 R. A. MILLIKEN CATHODE GLOW INDICATORTUBE FIGHE.'

3 Sheets-Sheet 1 March 22, 1966 R. A. MILLIKEN 3,242,370

CATHODE GLOW INDICATOR TUBE Filed Oct. 5, 1962 3 Sheets-Sheet 2 Mmh 22,1966 Filed Oct. 5, 1962 l .lill

R. A. MILLIKEN CATHODE GLOW INDICATOR TUBE MII lhlllll 3 Sheets-Sheet.odes constituting another group).

United States Patent O 3,242,370 CATHODE GLOW INDICATOR TUBE Rankin A.Milliken, Hayward, Calif., assigner, by mesne assignments, to Friden,Inc., San Leandro, Calif., a corporation of Delaware Filed Oct. 3, 1962,Ser. No. 228,124 9 Claims. (Cl. S13-109.5)

This invention relates to gaseous indicator glow tubes.

More particularly, this invention relates to indicator glow tubes of thetype particularly suited for use with circuits which utilize binaryprinciples of operation. Tubes of this type may be designated asdecoder-indicator tubes because they are capable, by reason of theirelectrode arrangement, of not only indicating numbers stored inelectronic counters but of also functioning to interpret, or decode, thepattern of electrical signals appearing upon the output terminals of anelectronic counter of the type in which said pattern of signals does notbear a simple one-to-one relationship, to the exciting terminals of saidindicating glow cathodes, or at least contributing substantialy to thisdecoding function by way of reduction of apparatus external to the tubenecessary for performance of this function.

Tube arrangements of this type may be seen in United States Patent No.2,906,906, upon which the present invention is an improvement.

Up to the present time decoder-indicator tubes of this type have notproved completely satisfactory because of the complexity of theirelectrode configurations.

Accordingly, one object of the instant invention is to provide animproved cathode indicator glow tube having combined anode-shieldelectrodes each of which performs functions hitherto performed byseparate electrodes.

Another object of the instant invention is to provide an improvedcathode indicator glow tube particularly suited for use in conjunctionwith binary-type counting circuits, and for providing a direct visiblereadout therefrom.

A still further object of the present invention is to provide astructural arrangement comprising mutually cooperating cathodes,combined anode-shield electrodes, insulators, :and sputter shieldelectrode which obviates the necessity of threading many cathodes andinsulators onto side rods, thereby making economically feasibleminiaturized assemblies of la compaetness hitherto `attainable only atvery great cost.

Briefly, the principles and objects of the instant invention may beembodied in a tube which comprises a gaslled envelope containing aplurality of indicator cathodes shaped in the form of desired, e.g.,numerical, indicia and capable of manifesting their presence bysustaining a cathode glow thereabout. If, for example, this tube is tobe used in a decade counter, it may contain indicator cathodes kin theform 'of lthe numerals 0 through 9. These indicator electrodes may bearranged in groups (e.g., all of the odd-number indicator cathodesconstituting one group, and all of the even-number indicator cath-According to the invention a combined anode-shield electrode will beassociated with the first group, and another electrically independentcombined anode-shield electrode will be associated with the secondgroup. Each combined anodeshield electrode Iserves the function ofshielding its associated group of indicator cathodes from excitation bythe other combined anode-shield electrode, or electrodes. In addition,each combined anode-Shield electrode serves the second function ofproviding an exciting field for provoking cathode glow upon any desiredone, or more, of its associated indicator cathodes. This is in contrastto prior art devices wherein the spurious excitation shielding andexciting functions were served by distinct and ICC different electrodesfor the same group of indicator cathodes. It will be apparent to thoseskilled in the art, then, that so combining these two functions in asingle combined anode-shield electrode for each group of indicatorcathodes makes possible the provision of a tube having all thecapabilities and advantages of prior art devices, yet at the same timebeing characterized by a reduced number of the electrodes.

In addition to the indicator cathodes and combined anode-shieldelectrodes, the tube of this invention may be equipped with a sputtershield electrode which at least partially screens the tube wall and baseconnections fnom sublimed cathode material, which may be at least inpart ionamin-ous, which may be at least partially conductive, or may, insome cases, be largely of insulating material and which may be equippedwith an electrical exciting connection, though such a .shield may be.dispensed with in some cases, and should not be considered a criticalpart of the invention.

The sputter shield electrode may, in a preferred embodiment, alsofunction mechanically to support the indicator cathodes and combinedanode-shield electrodes in desired relation within the tube by engaginga stack cornprising said cathodes and anode-shield electrodes andsupporting insulating means therefor. That is, the sputter shieldelectrode may not only embrace, or surround, the cathodes and combinedanode-shield electrodes for sputter shielding purposes, but may alsoengage the associated groups of cathodes and anode-shield electrodes forthe purpose of mechanical support. It is to be understood, however,ithat the advantages arising Ifrotm the provision of the combinedanode-shield electrodes may be embodied in a more conventional tubestructure (e.g., having side rods, or support posts, to mount theindicator cathodes as shown in United States Patent No. 3,042,826)without departing from the invention disclosed herein for minimizing thenumber of electrodes and base pins necessary in a device of the classdescribed herein.

It will further be apparent to those skilled in the art that the numberof contact pins, or base pins, necessary may be reduced to a minimum byproviding a contact pin for each of the combined anode-shield electrodesand a contact pin for each pair of indicator cathodes which may beselected one from one group and one from the other group. The sputtershield electrode may also be eliminated altogether, formed of insulatingmaterial, left floatingf or excited from a tapped impedance connectedacross the combined anode-shield electrode leads as shown in FIG. 6. Bythis last arrangement the number of necessary base pins is reduced toseven in a tube capable of providing decoding in a binary coded decimalcounter system. Other combinations of indicator cathode electrodes andcombined anode-shield electrodes may be made as required by a particularcircuit application. In addition, several sets each consisting of two ormore groups of indicator cathodes, at least one combined anode-shieldelectrode being associated with each group, may be provided so that asimultaneous readout of a plurality of characters may be achieved fromwithin a single envelope.

In operation of a decoder-indicator tube of the type of the instantinvention, a single indicator cathode in a group may be caused to glowby the application of the proper exciting voltage between the selectedindicator cathode and the combined anode-shield electrode associatedwith this indicator cathode. The combined anodeshield electrodesassociated with the other groups of indicator electrodes within thecommon envelope will prevent interaction between the combinedanode-shield electrode of the group including the selected indicatorcathode and the indicator cathodes of the other groups,

thereby preventing spurious, or undesired, ow of an indicator cathode ina group other than the group including the selected indicator cathode.

The invention is described in greater detail by reference to theaccompanying drawings wherein:

FIG. 1 is a perspective view of a tube embodying the instant invention;

FIG- 2 is a schematic representation of the tube of FIG. 1; l

FIG. 3 is an exploded pictorial view of a preferred indicator tubestructure according to the instant invention;

FIG. 4 shows the mutually non-obturating relationship of typicalindicator cathodes which may be used inV carrying out the instantinvention;

FIG. 5-a shows a spacing insulator frame according to the instantinvention;

FIGS. S-b and 5-c show positioning insulator frames according to theinstant invention;

FIGS. S-d and S-e show the combined anode-shield electrodes of theinstant invention; and

FIG. 6 is a schematic representation of an alternative embodiment of theinstant invention wherein the sputter shield electrode is excited by avoltage divider located internally of the tube envelope and connectedacross the combined anode-shield electrode leads.

Referring to the drawings, and more particularly to FIG. l, one form ofindicator tube according to the instant invention comprises an envelope1 which has been evacuated of air and lled with an ionizable gas, suchas neon, argon, or the like, at a suitable pressure, for example, in therange of about 40 to 120 mm. of mercury, and, if desired, one of theheavier gases or vapors, such as mercury. The envelope includes a baseportion, or stem press, through which conductive base pins, or contactpins 2 extend, and by means of which electrical connection may be madeto external electrical circuit means.

The tops of some, or all, of the contact pins 2 may be substantiallycoplanar, thus being adapted to support tube mount assembly 3 by meansof the lower mica end spacer 4, the mount assembly being constrainedagainst the tops of the base pins 2 by means, for instance, of clipssuch as shown at 17, which may be tweezerwelded to the top of one orseveral base pins, or by means of frictional engagement of lingers 5 onthe mica end spacers 4 with the interior of the wall of envelope 1,- orboth. It will be apparent to those skilled in the art that it may benecessary to shield the inner portions of base pins 2 associated withindicator cathodes 9, and the indicator cathode leads 10, from theanode-shield electrode base pins and leads. This may be done, forexample, by coating the inner portions of base pins 2 and cathode leads10 with glass frit, or Alundum, or by oxidizing the inner ends of thebase pins and the leads 10, or any combination of these expedients founddesirable by the tube designer. The envelope 1 also includes atransparent portion opposite cover mesh 18 (as shown in FIG. l) throughwhich al1 of the the indicator cathodes in the envelope may be viewed,combined anodeshield electrodes 6 and 7 (see, for example, FIG. 3) andcover mesh 18 being provided with sufliciently large foramens to besubstantially transparent. A sealed-off exhaust tubulation 11 isprovided in the stem press of envelope 1.

The electrode elements of a tube according to the invention may be seento include the following by comparison of FIGS. 1 and 3: a rst, or back,combined anode-shield electrode 6 made of conductive material, which maybe foraminous to only a suicient extent to expose its associatedindicator cathodes to view through the viewing portion of the envelope,or may be comprised to a larger degree, or entirely, of foraminousmaterial. A second, or front, anode-shield electrode, like the backanode-shield electrode, may be wholly or only partly foraminous. A groupof associated indicator cathodes is juxtaposed in association with eachof said anodeshield electrodes, said anode-shield electrodes 'serving toexcite the associated group of indicator cathodes or to shield theassociated group of indicator cathodes against the effects of otherelectrodes, alternately.

The sputter shield 8 may be directly connected to the inner end of oneof the base pins 2, which connection may serve to maintain the mountstructure 3 in position longitudinally of envelope 1, either ininsulated contact with the ends of the remaining base pins 2, or spacedtherefrom.

The indicator cathodes 9 `of the tube m-ay take substantially any`desired shape, for example, they may be in the shape of numbers,letters, arbitrary symbols such as plus or minus signs, or the like. Inone form ofthe tube, as shown in FIG. 4, the indicator cathodes may beprovided in the form yof numbers, the total of such indicator cathodesbeing ten in number, including the num-bers 0 through 9. The indicatorcathodes ymay be 'fabricated from any suitable metal, for example,stainless steel, aluminum, Nichrome, molybdenum, or the like; and theymay be made in any suitable fashion, for example, by etching, stamping,forming from wire, or the like.

The indicator cathodes 9 are .mounted in an aligned stack as shown inexploded view in FIG. 3, such that their planes are substantiallyparallel, and are suitably shaped and of such size that the separateelements thereof are displaced laterally with respect to each other sothat none is obstructed by the others, and each is' substantiallycompletely visible through the wall of envelope 1- opposite cover mesh18. In addition, each of the indicator cathodes within envelope 1 isprovided, -by means of indicator cathode leads- 10, with connection toone of the 4base pins 2 other than those used for supplying potential tothe combined anode-shield electrodes and the sputter shield electrode,one indicator cathode from the front group electrode, and one indicatorcathode from the back group being connected in common to one of the basepins 2. The arrangement of the connections of the anodeshi-eldelectrodes 6, 7, the sputter shield 8, and the indicator cathodes 9 withthe base pins 2 is shown in FIG. 2.

FIG. 3 shows the several parts of a tube of the instant invention inexploded view. As may be seen from this figure, the mount structure 3according to the instant invention is assembled by stacking a desiredplurality of the indicator cathodes 9 and the combined anodeshieldelectrodes 6 and 7, the indicator cathodes and anode-shield electrodesIbeing spaced apart by 4means of insulating spacing frames 13 and heldin desired relation to the apertures in spacing frames 13 4by means ofinsulating positioning frames 14, 32. As will be apparent to thoseskilled in the art from consideration of FIG. 3 the stack made up Aofthe indicator cathodes and combined anode-shield electrodes associated4with a given sputter shield electrode 8 and the insulating spacing and-positioning frames associated therewith is assembled and inserted intothe associated sputter shield electrode which first is closed at oneend, and after the insertion of this stack the -cover mesh 18 at theiother end of the sputter shield electrode is' fastened in place (e.g.,by means of spot welding) thereby maintaining the associated ndicatorcathodes and combined anode-shield electrodes in desired spaced relationwithin the combined sputter shield electrode. As shown in FIG. 3, anopening 31 is provided in the bottom wall of the sputter shieldelectrode whereby the leads 10 of the indi-cater cathodes may passthrough the sputter shield electrode without electrically contacting it.Leads 10 are preferably fabricated separately from the lower ears 12 ofindicator cathodes 9, and then by welding or otherwise axed thereto atthe proper angle to -pass out through channel 16 of insulating frames 14(FIG. 5-b) clearing the edge of slot 31 of the sputter shield electrodestructure by an amount determined to prevent spurious glow thereat. Theinsulating spacing frames 13 and the insulating positioning frames 14,32 may be fabricated from many types of insulating material well knownto those skilled in the art. Alternatively, due to the design of theseframes according to the instant invention, these frames may be punched,stamped, etched, or otherwise formed from oxidiza-ble metallicmaterials, and then treated, e.g., by dipping in an oxidizing solution,and subjected to heating in an oven, thereby producing an insulatingstructure adapted for use as an insulator in carrying out the instantinvention, which insulating structure has the advantage of being formed-by the simpler process available for producing metallic parts, ascompared with the processes available for producing thin insulatingparts. For instance, these insulating frames 13, 32, and 14 may beproduced from sheet nickel which is rst electroformed, stamped, orpunched, and then aluminized and oxidized, such a method being generallysuggested in United States Patent No. 2,891,184.

After assembly the mount structure 3 may be adapted for positioningwithin tube envelope 1 by passing end micas 4 over the ends thereof asfar as ears 24 provided on the longer sides thereof, passing ears 24through slots 22 in the end micas, and bending the outer portion of theears 24 along the outer surfaces of end micas 4, or distorting the outerportions as shown in FIG. 1. The completed mount assembly 3 and endmicas 4 may then be assembled upon the base pins 2 in the stem press bywelding the lower ears of the sputter shield electrode to one or morebase pins 2, by means of clips 17, or both. The cathode leads andcombined anode-shield electrode leads may then -be connecte-d toappropriate base pins 2, as by tweezer Welding, the stern and envelopesealed, and the envelope evacuated through tu-bulation 11, which is thensealed olf.

When assembled as described above, the indicator cathodes 9 will Ibenonmutually-interferingly registered as shown in FIG. 4, wherein thecathodes making up the full set, 0 through 9 `are shown.

The contour of 1one of the insulating spacing frames 13 is shown in FIG.5-a. It will be noted from this figure that the upper and lower edges ofthe frame aperture are provided with inwardly projecting portions whichserve to maintain indicator cathodes 9 and combined anode-shieldelectrodes 6, 7 in spaced relation, and also serve to present only thenumeral-defining portions of cathodes 9 to view through cover mesh 18.

The insulating positioning frames 14, 32 are illustrated in FIGS. S-band 5-c. It will be noted from this ligure that the insulatingpositioning frames 14 are provided with inward projections ofsubstantially the same contour as the inward projections in insulatingspacing frames 13, but provided with ear receivers in which the ears 12of the associated indicator cathode will be emplaced during assembly.Further, the insulating positioning frames 14 are provided with leadchannels 16 communicating from one of the ear receivers 15 through thelower portion of the frame 14. As may be seen from FIG. 3, the indicatorcathode leads 10 will pass through the channels 16, and will beconstrained by the limited lateral extent of lead channel 16 fromcontacting the edges of slot 31 in the sputter shield electrode 8. Itwill be apparent to those skilled in the art that, by the provision ofthis particular lead channel structure and cooperating orientation andpositioning of indicator cathode leads and combined anode-shieldelectrode leads 10, a controlled spacial relation between the indicatorcathode leads 10 and the edges of slot 31 may be maintained, therebytaking advantage of the lower limb of the Paschens Law curve for mutualinsulation purposes and assuring maximum isolation between the leads ofadjacent cathodes.

FIG. 6 indicates an alternative construction which may be employed in adevice according to the invention. In this alternative embodiment thecombined anode-shield electrodes 6 and 7 have connected therebetween apair of impedances 19 (usually equal) the common point of which isdirectly connected to sputter shield electrode 8 by means of connection26. It will be apparent to those skilled in the art that, in certaincircuits in which the tube ofv the invention may be employed, thepotential thus applied to sputter shield electrode 8 will result insuppressing sputter upon the walls of the envelope, while notnecessitating the use of an eighth base pin.

As will be apparent to those skilled in the art, the principles of theinstant invention may also be embodied in a tube which includes morethan two sets of groups of electrodes. A typical binary coded decimalcounter system in which the tube of the instant invention may beemployed is shown in United States Patent No. 2,906,906. Y y

Since numerous changes may be made in the abovedescribed apparatus, anddierent embodiments of the invention may be made without departing fromthe spirit thereof, it is intended that all the matter contained in theforegoing description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An indicator tube comprising: a iirst group of indicator cathodesadapted to glow, a second group of indicator cathodes adapted to glow,an electrode associated with each of said groups of cathodes, saidassociated electrodes being at least partially located in the spacebetween-said groups of cathodes, said space being otherwise free ofelectrodes, said electrode associated with said irst group of cathodesbeing adapted to excite at least one of said iirst group of cathodes toglow and being further adapted to prevent said first group of cathodesfrom glowing when any of said second group of cathodes is glowing, andsaid electrode associated with said second group of cathodes beingadapted to excite at least one of said second group of cathodes to glowand being further adapted to prevent said second group of cathodes fromglowing when any one of said irst group of cathodes is glowing.

2. An indicator tube comprising: a rst group of indicator cathodesadapted to glow, a second group of indicator cathodes adapted to glow, acombined anodeshield electrode associated with each of said groups ofcathodes, each of said combined anode-shield electrodes being locatedadjacent its associated group of cathodes, the space between saidcombined anode-shield electrodes being free of electrodes, whereby eachof said combined anode-shield electrodes is adapted to excite at leastone of its associated cathodes to glow and is also adapted to shield itsassociated group of cathodes from glowing when any of the cathodes ofthe group associated with the other anode-shield electrode is excited toglow, and a sputter shield connected to voltage dividing means connectedbetween said combined anode-shield electrodes, said cathodes,electrodes, sputter shield, and voltage dividing means all beingcontained within a common envelope.

3. An indicator tube comprising: a plurality of sets of groups ofindicator cathodes adapted to glow and pairs of combined anode-shieldelectrodes interposed in the spaces between said groups of said sets,each of said combined anode-shield electrodes being adapted to excite atleast one of its adjacent group of cathodes to glow and to coact inpreventing its adjacent group of cathodes from glowing when any cathodeof any of the other groups of its set is excited to glow by an adjacentcombined anode-shield electrode, said spaces being otherwise free ofelectrodes.

4. An indicator tube comprising: a plurality of sets of groups ofindicator cathodes adapted to glow and pairs of combined anode-shieldelectrodes interposed in the spaces between said groups of said sets,said spaces being otherwise free of electrodes.

5. An indicator tube comprising: a first group of five indicatorcathodes adapted to glow, a second group of live indicator cathodesadapted to glow, a pair of combined anode-shield electrodes interposedbetween said groups of cathodes, the space between said groups ofcathodes being free of further electrodes, and an envelope having at themost seven contact pins for making electrical contact between saidcathodes and combined anodeshield electrodes and apparatus locatedexternally thereof passing therethrough.

6. An indicator tube comprising: a plurality of sets of groups ofindicator cathodes adapted to glow, pairs of combined anode-shieldelectrodes interposed between said groups of said sets, each of saidcombined anode-shield electrodes being adapted to excite at least one ofits adjacent group of cathodes to glow and to coact in preventing itsadjacent group of cathodes from glowing when any cathode of any of theother groups of its set is excited to glow by an adjacent combinedanode-shield electrode, and an envelope enclosing said cathodes andcornbined anode-shield electrodes and having disposed therethrough ncontact pins,- where and C equals the number of cathodes in one of saidgroups, S equals the number of said sets, and G equals the number ofsaid groups.

7. An indicator tube comprising: a first group of indicator cathodesadapted to glow, a second group of indicator cathodes adapted to glow,and a pair of cornbined anode-shield electrodes interposed between saidgroups of cathodes, the space between said cathodes being otherwise freeof electrodes, each of said combined anodeshield electrodes beingadapted to excite its adjacent group of cathodes to glow and to preventits adjacent group of cathodes from glowing when one or more of theotherr of said groups of cathodes is excited to glow by its adjacentcombined anode-shield electrode, and coacting sputter shielding meanscomprising an insulating spacer member defining an enclosure at leastpartially enclosing said groups of cathodes and said combinedanodeshield electrodes.

8. An electrode assembly for use in a glow indicator tube comprising: aplurality of indicator cathodes, a plurality of combined anode-shieldelectrodes, a first plurality of insulating frames surrounding each ofsaid indicator cathodes and each of said combined anode-shieldelectrodes, a second plurality of insulating frames insulatedly spacingsaid first plurality of insulating frames, and a sputter shield engagingsaid frames, thereby maintaining said cathodes and anode-shieldelectrodes inV mutuallly fixed insulated relation without the use ofother relation maintaining means. v

9. An electrode assembly for use in a glow indicator tube comprising;aplurality of indicator cathodes, a plurality of combined anode-shieldelectrodes, a first plurality of insulating frames surrounding each ofsaid indicator cathodes and each of said combined anode-shieldelectrodes, a second plurality of insulating frames insulatedly spacingsaid rst plurality of insulating frames, and a sputter shield engagingsaid frames and clamping said frames, indicator cathodes, and combinedanode-shield electrodes together, said frames, cathodes, and anodeshieldelectrodes being free of continuous members passing therethrough.

References Cited by the Examiner UNITED STATES PATENTS Re. 25,65510/1964 McCauley et al. 313-1095 X 2,848,638 8/1958 Smith 313-10952,906,906 9/1959 McCauley et al. 313- 210 X GEORGE N. WESTBY, PrimaryExaminer.

D. E. SRAGOW, Assistant Examiner.

1. AN INDICATOR TUBE COMPRISING: A FIRST GROUP OF INDICATOR CATHODESADAPTED TO GLOW, A SECOND GROUP OF INDICATOR CATHODES ADAPTED TO GLOW,AN ELECTRODE ASSOCIATED WITH EACH OF SAID GROUPS OF CATHODES, SAIDASSOCIATED ELECTRODES BEING AT LEAST PARTIALLY LOCATED IN THE SPACEBETWEEN SAID GROUPS OF CATHODES, SAID SPACE BEING OTHERWISE FREE OFELECTRODES, SAID ELECTRODE ASSOCIATED WITH SAID FIRST GROUP OF CATHODESBEING ADAPTED TO EXCITE AT LEAST ONE OF SAID FIRST GROUP OF CATHODES TOGLOW AND BEING FURTHER ADAPTED TO PREVENT SAID FIRST GROUP OF CATHODESFROM GLOWING WHEN ANY OF SAID SECOND GROUP OF CATHODES IS GLOWING, ANDSAID ELECTRODE ASSOCIATED WITH SAID SECOND GROUP OF CATHODES BEINGADAPTED TO EXCITE AT LEAST ONE OF SAID SECOND GROUP OF CATHODES TO GLOWAND BEING FURTHER ADAPTED TO PREVENT SAID SECOND GROUP OF CATHODES FROMGLOWING WHEN ANY ONE OF SAID FIRST GROUP OF CATHODES IS GLOWING.